it definitely seems very up to preference, i had to play a lot of hag because getting 15 kills without her hex totem being sacrifices took a long time and started to eventually get some good matches as her...
for reference, what i thought going for their trophies:
the trapper: his adept took a long time to get... i dont really like his traps and didnt use them a lot.. i didnt play him that much because his trap trophy had low requirements
wraith: didnt require much thought to play which was nice, go invisible and go after people lol
hillbilly: i usually just hit people and dont use his chainsaw because its so hard to use. his 50 chainsaw trophy was annoying
nurse: sometimes get lucky and get good games as her but most my matches, i do awful, she's so hard to play
the hag: played the most of her to get her trophies, actually pretty fun to play
the doctor: pretty easy to play, im able to tell where people are because of his ability
huntress: im never able to hit anyone with her hatchets, barely played her becuse shes not needed for platinium